1. Field of the Invention
The present invention relates to guardrail structure and more particularly to a metal tube structure for guardrail with improved characteristics.
2. Description of Related Art
A conventional guardrail comprises two parallel metal tubes with a protective board mounted in between. Such metal tube 100 is shown in FIGS. 14 and 15 and is formed by bending an elongate strip of steel sheet material 90 into a hoop, pressing from underside to form an elongate groove 92 having a section of inverted U and a top abutment plate 91, and welding the hoop along a weld line 93 to finish the product.
However, the prior art suffered from several disadvantages. For example, an additional polishing step is required to smooth the weld line 93. Further, the metal tube 100 may be not straight after the welding. Furthermore, the manufacturing process is time consuming, not economical. Also, both welding and polishing are risky jobs and may contaminate the environment.
Thus, it is desirable to provide an improved metal tube structure for guardrail in order to overcome the above drawbacks of the prior art.
It is an object of the present invention to provide a metal tube structure for guardrail so as to effect a mass production through a simple process.
It is another object of the present invention to provide a metal tube structure for guardrail in which no welding and polishing is required for maintaining a straightness of the metal tube during the manufacturing process. As such, advantages such as a saving of time, a reduction of cost, and a safe working environment without contamination are obtained.
It is still another object of the present invention to provide a metal tube structure for guardrail in which the metal tube can be made smaller since the metal tube is assembled with the variety depths of inner abutment mechanism. This in turn can reduce a consumption of material.
It is a further object of the present invention to provide a metal tube structure for guardrail in which no additional polishing is required since there is no weld line on the abutment member. As a result, a quality of the finished product is increased.
It is still further object of the present invention to provide a metal tube structure for guardrail in which different depths of troughs of inner abutment mechanisms are made possible for being adapted to a single metal tube. This effect a great flexibility in configuring the guardrail.
To achieve the above and other objects, the present invention provides a metal tube for guardrail comprises a C section-shaped metal tube having two lengthwise bent ends each having a fastening member, and an inner abutment mechanism each having a lengthwise abutment member and a mating fastening member at either end thereof engaged with the fastening member of the metal tube when the inner abutment mechanism is inserted into the metal tube for securing each metal tube and the corresponding inner abutment mechanism together to form a complete assemblying metal tube for guardrail.
Preferably, to achieve the above and other objects, the present invention provides a guardrail comprising a pair of parallel metal tubes each having a section of C, a lengthwise gap, and two first bent ends along the gap, each first bent end having a lengthwise inner section and a lengthwise first groove; a pair of inner abutment mechanisms each having a section of U, a horizontal abutment member, a trough defined by two vertical sections and the abutment member, and a pair of second bent ends along the trough, each second bent end having two lengthwise outer sections and two lengthwise second grooves wherein the second bent end is put on the inner section with the outer section inserted into the first groove and the inner section inserted into the second groove for securing each metal tube and the corresponding abutment mechanism together; and a protective board having either end urged against the abutment member and the first bent ends, thereby securing the protective board between the abutment mechanisms.
In one aspect of the present invention, either vertical section is bent to cause the vertical section and the first bent end to be at the same flat surface urged against the protective board.
Preferably, to achieve the above and other objects, the present invention further provides a guardrail comprising a pair of parallel metal tubes each having a section of C, a lengthwise gap, and two vertical ends along the gap, each vertical end having a lengthwise horizontal inner section; a pair of inner abutment mechanisms each including a horizontal abutment member having two lengthwise bent ends and two lengthwise grooves in the bent ends; wherein the bent end is put on the inner section with the inner section inserted into the groove for securing each metal tube and the corresponding abutment mechanism together; and a protective board having either end urged against the abutment member and the vertical ends, thereby securing the protective board between the abutment mechanisms.
In another aspect of the present invention, either abutment member is bent to have a section of U so that the protective board is urged by the vertical ends and either abutment member.
Preferably, to achieve the above and other objects, the present invention further provides a metal tube structure for guardrail comprising:
an outer metal tube having a section of C, a lengthwise gap formed between two flat ends, a horizontal inner section formed perpendicular to each of the flat end; and
an inner abutment mechanism having a horizontal abutment member which has two bent ends each with a groove formed therein;
wherein each of the horizontal inner section of the outer metal tube is inserted into each of corresponding groove of the inner abutment mechanism together to form a complete metal tube for guardrail.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.